Practice Exam Flashcards

(25 cards)

1
Q

Which two types of molecular interactions are most important in stabilising the structure of the DNA double helix?

A

Hydrogen bonds an hydrophobic interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

RNA structure:

A
  • RNA consists of unbranches chains of nucleotides
  • the phosphodiester links in RNA join the 5’ position of one nucleotide with the 3’ position of the adjacent nucleotide
  • the bases in RNA are uracil, adenine, guanine, cytosine
  • RNA is single stranded = relative amounts of purines and pyrimidines are not fixed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Restriction endonucleases =

A

Cut the phosphodiester bonds between adjacent nucleotides in DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Quinolones =

A

Inhibit DNA gyrase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Actinomycin D =

A

Inhibits transcription by binding to DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cycloheximide =

A

Inhibits protein synthesis in eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Chloramphenicol =

A

Binds to the prokaryotic 70s ribosome particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which amino acid is sulphur present in =

A

Cysteine and methionine

= only these form disulphide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Km =

A

Michaelis constant = the substrate concentration which gives 50% of the maximal rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In a lineweaver-burk plot :

A

Intersection on Y axis = 1/Vmax

Intersection on x axis = -1/Km

Gradient = Km/Vmax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which amino acid is present at the active site of pancreatic ribonuclease and is involved in the catalysis of RNA hydrolysis ?

A

Histidine + lysine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the substrates of DNA polymerase enzymes ?

A

Template DNA
Primer with 3’-OH
Deoxynucleotide trisphosphates
Mg2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the products of DNA polymerase enzymes?

A

Pyrophosphate

The growing strand is one nucleotide longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does DNA polymerase 1 differ from 3?

A
DNA polymerase 3 =
Faster
More processive 
Lacks 5’ > 3’ exonuclease activity 
Has multiple subunits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Differences between primase and DNA polymerase enzymes?

A
  • primase makes RNA and doesn’t need primer

- DNA polymerase makes DNA and requires a primer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What role does 3’-OH on the ribose play in the polymerase reaction ?

A

Nucleophilic attack of the a-phosphorous of the incoming dNTP

17
Q

Give two examples of posttranscriptional modification of RNA in bacteria -

A

Base modification in tRNA/rRNA

Ribose methylation in tRNA/rRNA

18
Q

Which type of bacteria

RNA is not subject to processing ?

19
Q

Which enzyme synthesises mRNAs in eukaryotes?

A

RNA polymerase 2

20
Q

What posttranscriptional modification occur at the ends of eukaryotic mRNAs ?

A

Capping at 5’ end
Tail addition at 3’ end
Cleavage prior to addition of tail

  • happens in the nucleus
21
Q

Splicing =

A

Excision of introns sequences from the mRNA primary transcript and joining of the exons

22
Q

Low Km =

A

Higher affinity of an enzyme for its substrate

23
Q

Competitive inhibitor effectors on…

A

Km increase

Vmax unchanged

24
Q

Non competitive inhibitor effects on…

A

Km unchanged

Vmax decrease

25
Collagen can be found…
Skin, bones, cartilage, tendons, teeth